It is known to polymerize alpha-olefins in the range of from 5 to 20 carbon atoms either thermally or in the presence of catalysts to give products having viscosities in the lubricating oil range. Normally such lubricants have undesirably high pour points, e.g. in the range of about 0.degree. F to +70.degree. F. Such products are not suitable for applications where low pour points and low viscosities are required, as for example, in transformer oils. Lubricating oils having low pour points and low viscosities making them useful as electrical insulating oils for transformers and switches are normally derived either from naphthenic crude oils, which are becoming scarce, or by extensive and costly processing of conventional lubricating oil distillates. The present invention provides a process for preparing very low pour point, low viscosity products by polymerizing alpha-olefins of from 5 to 20, preferably 10 to 14 carbon atoms in the presence of a molecular-sieve-type catalyst.